This invention relates to a band device for obstructing the well of a hub of a wheel rim, particularly wheel rims for pneumatic tires, and to fastening devices which are particularly suitable for such bands.
Conventional pneumatic tires are commonly mounted on a wheel rim. Typically, the wheel rim has a hub with raised flanges at its axial ends for retaining the beads of the tire. When the tire is inflated, the internal pressure forces the beads against the inside surfaces of these flanges to retain the tire securely to the rim. If the tire is of the tubeless type, these flanges also act to seal against the beads to prevent any loss of air pressure.
The bead of the tire is relatively inextensible and has an internal diameter less than the outside diameter of the bead retaining flanges of the hub. To make it easier to install the tire on the wheel rim, the hub of such wheel rims commonly have an annular well which extends radially inwardly. This is sometimes called a drop-center type wheel rim. When it is desired to install the tire onto the wheel rim, one side of the bead can be placed around the bead retaining flange and into the well, thus enabling the diametrically opposing side of the bead to be placed over the bead retaining flange on the other side of the wheel rim. Removal of the tire is accomplished in the reverse manner.
After the tire is installed and the tire inflated with its bead seated against the flanges, the well serves no function. The presence of this well, however, has been found to pose safety problems. When pressure is unintentionally lost from the tire due to a blow out or puncture during operation, the well again becomes available to the bead of the tire. If the bead of the tire falls into this well, it is possible for the diametrically opposite side of the bead to unintentionally fall off the bead retaining flange, and thence for the entire bead to fall off the flange. When the bead of the tire is lost from the bead retaining flange, serious loss of control of a vehicle upon which the tire is mounted can result.
Removable, band-type well obstructors have been proposed for obstructing this well so that, in the event of deflation of the tire during operation, the interior of the well will not be available to the bead of the tire, thus insuring that the tire will remain on the wheel rim. When it is desired to remove the tire during maintenance operations, the tire is deflated and one bead pushed inwardly so as to expose the well obstructing band. The band can then be removed so that the tire can be removed in the normal manner. Such band devices are disclosed in U.S. Pat. No. 3,933,392, issued on Jan. 20, 1976 to William Neil Wells, U.S. Pat. No. 4,122,882 issued Oct. 31, 1978 to Fisher et al., and U.S. Pat. No. 4,391,317, issued July 5, 1983 to Bernard J. Savage.
The bands disclosed in these patents are retained around the well with rectangular, bent metal tabs which are adapted to enter the well, and to abut against the base of the well. The strength of the rectangular bent tabs is limited, however, and after unintentional deflation under heavy loads or at high speeds, the weight of the vehicle and related forces acting on the bead of the tire can crush the band and the rectangular tabs rendering the well obstructing band ineffectual. In addition, the rectangular tabs have only limited frictional resistance against the base of the well, and thus can permit undesirable rotation of the band with respect to the hub.
The bands are typically held onto the hub in circumferential tension by the use of threaded fasteners pulling together adjacent ends of the band. Where the wheel rim is large, the band may be in two, semi-circular portions, connected with a solid link at one pair of ends, and a threaded fastener at the other pair of ends.
A threaded fastener, as proposed in U.S. Pat. No. 4,391,317, uses an Allen head screw, a bar washer and a bar nut for drawing together the adjacent ends. Although the bar nut and bar washer fastener is generally sturdy, the screw has a tendency to loosen. Furthermore, maintenance personnel who change tires are occasionally unaccustomed to well obstructor bands. Because of this, such installers may misplace or misuse the parts of the fasteners which are necessary to securely hold the band onto the hub. This may be particularly acute where bar nuts are used, because these are not readily available, and if lost, the temptation to use a conventional fastener which was not designed to be used is great. If the fastener is installed improperly, the well obstructor band can become loose, thus resulting in a dangerous condition.
The solid links which have been proposed include a disk-ended dog bone link as disclosed in U.S. Pat. No. 4,122,882, or a bent strip of metal as in U.S. Pat. No. 4,391,317. The disk-ended dog bone link has not been found to be entirely satisfactory, however, because the round disks have a tendency to wedge open the openings in the corresponding flanges of the band portions through which the link passes. The bent strip of metal has limited strength.